Small image sensors continue to improve in cost and performance and have become ubiquitous in smart phones, notebook computers, tablets and many other devices. At the same new device types such as headsets, glasses, dashboard cameras, and autonomous vehicles continue to emerge. The common CMOS (Complementary Metal Oxide Semiconductor) image sensor that is used in most digital cameras has an array of photodetectors. Usually there is one photodetector for each pixel. The sensor is well suited to capture and measure visible light.
The same sensor is also able to capture and measure NIR (Near Infrared) light. As a result, new applications are being developed to exploit this property. Biometric authentication and depth cameras, for example have been developed to use NIR. NIR has a benefit of revealing features that are not visible in visible light. Such features may reflect NIR but not visible light or the system may incorporate invisible, NIR illumination that does not distract or otherwise influence the user.
Imaging applications extending the range of spectral sensitivity beyond the visible range are coming to market. These applications include face recognition, iris scanning, and multi-spectral imaging for analyzing chemical content to name a few examples.